Current pharmacotherapy or alcohol and drug addiction yields relatively low probability for attaining long- term recovery. The recent dramatic reduction in R&D by the pharmaceutical industry for novel medications to treat psychiatric conditions, particularly substance use disorders, provides a strong impetus to repurpose currently available compounds that may be effective treatment alternatives. Orally available, brain-penetrant ?1-noradrenergic (NE) receptor antagonists are widely used to treat hypertension. Additionally, ?1-NE antagonists are increasingly used to treat post-traumatic stress disorder (PTSD), consistent with the well- documented role of NE in mediating multiple behavioral and physiological processes in stress. Stress is a significant contributor to alcohol/drug relapse. Stress-related reinstatement is a well-validated animal model of addiction and ?1-NE antagonists reduce relapse in this animal model. NIAAA Director George Koob has made strong calls for translational research on stress-mechanisms in humans. This preclinical evidence in animals suggests the use of ?1-NE antagonists may be useful in relapse prevention including stress-related relapse. To test this hypothesis, we propose two complementary preclinical and clinical objectives in humans: 1. To translate the preclinical evidence from animal models to stress-induced relapse in humans via direct pharmacological antagonism of the NE system in abstinent alcoholics with doxazosin, an ?1-NE blocker. 2. To screen the efficacy of doxazosin to target stress-related relapse mechanisms in abstinent alcoholics as a cost-effective first step to repurpose this ?1-NE antagonist for relapse prevention in addiction. Thes two objectives will be accomplished in a randomized controlled trial (RCT) of recently abstinent alcoholics, to examine the efficacy of 8 mg doxazosin (vs. placebo, between-subjects) on stress reactivity and clinical outcome measures (e.g., drinks/week, alcohol craving) during a 8 week treatment period. We assess doxazosin's impact on stress-related relapse mechanisms using a well-validated human model of stressor reactivity (NPU task) at baseline (pre-treatment), and after 4 weeks and 8 weeks of treatment. The NPU task has strong translational ties to both methods and measures from the preclinical literature in animals. This task has demonstrated reliable, robust effects of drug administration and drug deprivation in drug dependent users. As such, it serves as an attractive early surrogate endpoint post-treatment to assess treatment efficacy and examine stress mechanisms. Repurposing existing pharmaceutical agents has recently been promoted by NIH director, Francis Collins, as a research priority. Tom Insel and others have strongly advocated for the development and use of early surrogate endpoints in clinical research. This project aligns well with the NIMH RDoC focus on dimensions of observable behavior and neurobiological measures in psychopathology research. This project also anticipates changes at NIMH to capitalize on simultaneous examination of mechanism and outcome in RCTs.